Gas turbine engines, such as those which power aircraft and industrial equipment, employ a compressor to compress air that is drawn into the engine and a turbine to capture energy associated with the combustion of a fuel-air mixture. Duct and/or liner interfaces for engine components (including exhaust systems and nacelles) often require sealing between components. Seals are used in engines to isolate a fluid from one or more areas/regions of the engine. For example, seals control various parameters (e.g., temperature, pressure) within the engine and ensure proper/efficient engine operation and stability.
It can be difficult to provide adequate sealing over the operational range of an engine due to a variety of factors. Such factors include irregular/odd-shaped component profiles, component tolerances, nominal/normal component deflections (e.g., relative motion between components), and large magnitude deflections (e.g., deflections resulting from increased/maximum maneuvers).
A metallic finger seal that includes overlapping sheet metal segments is a known technique that is used for sealing. For example, U.S. patent application publication No. 2015/0354384 (hereinafter the '384 publication) describes/illustrates embodiments of an engine incorporating a finger seal. The contents of the '384 publication are incorporated herein by reference.
A finger seal may be designed for a normal range of motion within a range of acceptable elastic strain. Under excessive deflection (e.g., deflection exceeding a threshold), the seal may be crushed or deflected to the point where permanent plastic deformation occurs. This deformation results in loss of subsequent sealing capability/effectiveness.
To accommodate a larger range of motion/deflection, a packaging geometry of the seal may be increased. However, physical space might not be available in an engine to accommodate a large seal (or, analogously, including such a large seal comes with a cost in the form of space that is sacrificed/used in the engine to accommodate the seal). This may be particularly true in the context of existing/legacy engine hardware/platforms, where there might not be an opportunity to include a large seal due to existing constraints.